Friday, November 21, 2008

Redistribution Gotcha

In the above scenario the loopback interface address is introduced into OSPF via the 'redistribute connected' command on router 3. Following this OSPF is redistributed into the RIP domain on router 3 using 'redistributed ospf 1 subnets metric 5'.

Upon examining the routing table on router 4 i was surprised to find no route for 150.1.3.3 present! This is to do with an anomoly with redistribution on the device performing the redistribution itself. When OSPF is redistributed into RIP it will carry all OSPF routes EXCEPT locally redistributed ones. In this instance RIP must pull such routes in explicitly using the 'redistribute connected' command itself.

Notes....1)When redistributing in IPV6 it is also necessary to incorporate the 'redistribute connected' . Without this local interfaces are not redsitributed by default.

2) When redistributing rip into OSPF any route for directly connected interfaces ARE taken across by default. :-)! 3) With OSPF and EIGRP mutual redistribution connected routes are taken across by default.

Final note to self!!! With redistribution watch out for connected routes! particularly with RIP and IPV6.